ACVIM Consensus Statement
J Vet Intern Med 2009;23:1142 1150
Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide the
veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of
clinically important animal diseases. The ACVIM Board of Regents oversees selection of relevant topics,
identification of panel members with the expertise to draft the statements, and other aspects of assuring the
integrity of the process. The statements are derived from evidence-based medicine whenever possible and the
panel offers interpretive comments when such evidence is inadequate or contradictory. A draft is prepared
by the panel, followed by solicitation of input by the ACVIM membership, which may be incorporated into
the statement. It is then submitted to the Journal of Veterinary Internal Medicine, where it is edited prior to
publication. The authors are solely responsible for the content of the statements.
Guidelines for the Diagnosis and Treatment of Canine Chronic
Valvular Heart Disease
C. Atkins, J. Bonagura, S. Ettinger, P. Fox, S. Gordon, J. Haggstrom, R. Hamlin, B. Keene (Chair),
V. Luis-Fuentes, and R. Stepien
Key words: Cardiology; Cardiovascular; Heart failure; Therapy.
his is the report of the American College of Veteri-
nary Internal Medicine (ACVIM) Specialty of
T
Abbreviations:
Cardiology consensus panel convened to formulate
ACEI angiotensin converting enzyme inhibitors
guidelines for the diagnosis and treatment of chronic val-
ACVIM American College of Veterinary Internal Medicine
vular heart disease (CVHD, also known as endocardiosis
CRI constant rate infusion
and myxomatous valve degeneration) in dogs. It is esti-
CVHD chronic valvular heart disease
mated that approximately 10% of dogs presented to
ECG electrocardiography
primary care veterinary practices have heart disease, and
LA left atrium
CVHD is the most common heart disease of dogs in
LV left ventricle
many parts of the world, accounting for approximately
MR mitral regurgitation
75% of canine cases of heart disease cases seen by veter-
inary practices in North America.
CVHD most commonly affects the left atrioventricu-
lar or mitral valve, although in approximately 30% of before the clinical onset of heart failure. When large
cases the right atrioventricular (tricuspid) valve also is breed dogs are affected by CVHD, the progression of the
involved. The disease is approximately 1.5 times more disease appears to be more rapid than that observed in
common in males than in females. Its prevalence is also small breed dogs.2 Cavalier King Charles Spaniels are
higher in smaller (o20 kg) dogs, although large breeds predisposed to developing CVHD at a relatively young
occasionally are affected.1 In small breed dogs, the dis- age, but the time course of their disease progression to
ease generally is slowly but somewhat unpredictably heart failure does not appear to be markedly different
progressive, with most dogs experiencing the onset of a from that of other small breed dogs except for the early
recognizable murmur of mitral valve regurgitation years age of onset.3,4
The cause of CVHD is unknown, but the disease ap-
pears to have an inherited component in some breeds
From the Department of Clinical Sciences, North Carolina State
studied.5,6 CVHD is characterized by changes in the cel-
University, Raleigh, NC (Atkins, Keene); Department of Veterinary
lular constituents as well as the intercellular matrix of the
Clinical Sciences (Bonagura), Department of Veterinary Biosciences
valve apparatus (including the valve leaflets and chordae
(Hamlin), The Ohio State University, Columbus, OH; California
Animal Hospital, Los Angeles, CA (Ettinger); Department of tendineae).7,8 These changes involve both the collagen
Medicine, Animal Medical Center, New York, NY (Fox); Depart-
content and the alignment of collagen fibrils within the
ment of Small Animal Clinical Science, Texas A&M University,
valve.9,10 Endothelial cell changes and subendothelial
College Station, TX (Gordon); Department of Clinical Sciences,
thickening also occur,11 although affected dogs do not
University of Agricultural Sciences, University of Uppsala, Uppsala,
appear to be at increased risk for arterial thromboembo-
Sweden (Haggstrom); Royal Veterinary College, VCS, University of
lism or infective endocarditis. Mitral valve prolapse is a
London, London, UK (Luis-Fuentes); and Department of Medical
Sciences, University of Wisconsin-Madison, Madison, WI (Stepien). common complication of myxomatous valve degenera-
Corresponding author: Bruce Keene, Department of Clinical Sci-
tion and represents a prominent feature of CVHD in
ence, 4700 Hillsborough Street, North Carolina State University,
some breeds.6,12 Progressive deformation of the valve
Raleigh, NC 27606; e-mail: [e-mail].
structure eventually prevents effective coaptation and
Submitted June 12, 2009; Revised August 7, 2009; Accepted
causes regurgitation (valve leakage). Progressive valvu-
August 17, 2009.
lar regurgitation increases cardiac work, leading to
r
Copyright 2009 by the American College of Veterinary Internal
ventricular remodeling (eccentric hypertrophy and inter-
Medicine
10.1111/j.1939-1676.2009.0392.x cellular matrix changes) and ventricular dysfunction.
Canine Chronic Valvular Heart Disease 1143
Abnormal numbers or types of mitogen receptors (eg, A newer classification system that might more objec-
any of the subtypes of serotonin, endothelin, or angio- tively categorize patients in the course of their heart
tensin receptors) on fibroblast cell membranes in the disease has been developed, and this scheme was used by
valves of affected dogs may play a role in the pathophys- the panel for consensus recommendations. The goal was
iology of the valvular lesions.13 Systemic or local to link severity of signs to appropriate treatments at each
metabolic, neurohormonal or inflammatory mediators stage of illness. In formulating these guidelines, the con-
(eg, endogenous catecholamines and inflammatory cyto- sensus panel adapted the 2001 American College of
kines) also may influence progression of the valve lesion Cardiology/American Heart Association classification
or the subsequent myocardial remodeling and ventricular system for the treatment of heart disease and failure in
dysfunction that accompany long-standing, hemody- human patients to the management of canine CVHD.19
namically significant valvular regurgitation. However, In this approach, patients are expected to advance from 1
these factors are poorly understood at this time.14 stage to the next unless progression of the disease is al-
The prevalence of CVHD increases markedly with age tered by treatment.
in small breed dogs (with up to 85% showing some evi- The classification system presented below and used in
dence of the lesion at necropsy by 13 years of age), but these guidelines is meant to complement, not replace,
the presence of the pathologic lesion does not necessarily functional classification systems. The new system de-
indicate that a dog will develop clinical signs of heart scribes 4 basic stages of heart disease and failure:
failure. Like the underlying cause of the disease, the fac-
Stage A identifies patients at high risk for developing
tors that determine the progression of the lesion remain
heart disease but that currently have no identifiable
unknown, although age, left atrial size, and heart rate
structural disorder of the heart (eg, every Cavalier
have been shown to predict outcomes.15,16
King Charles Spaniel without a heart murmur).
Stage B identifies patients with structural heart disease
(eg, the typical murmur of mitral valve regurgitation is
Classification of Heart Disease and Heart Failure
present), but that have never developed clinical signs
Heart failure is a general term that describes a clinical
caused by heart failure. Because of important clinical
syndrome that can be caused by a variety of specific heart
implications for prognosis and treatment, the panel
diseases, including CVHD. Heart failure from any cause is
further subdivided Stage B into Stage B1 and B2.
characterized by cardiac, hemodynamic, renal, neurohor-
Stage B1 refers to asymptomatic patients that have
monal, and cytokine abnormalities. The classification
no radiographic or echocardiographic evidence of
systems for heart failure most familiar to veterinarians are
cardiac remodeling in response to CVHD.
the modified New York Heart Association (NYHA)17 and
Stage B2 refers to asymptomatic patients that have
International Small Animal Cardiac Health Council18
hemodynamically significant valve regurgitation,
functional classification systems, both of which were de-
as evidenced by radiographic or echocardiograph-
signed to provide a framework for discussing and
ic findings of left-sided heart enlargement.
comparing the clinical signs of patients in heart failure.
Stage C denotes patients with past or current clinical
These functional classification systems vary in their
signs of heart failure associated with structural heart
details, but both serve as semiquantitative schemes for
disease. Because of important treatment differences be-
judging the severity of a patient s clinical signs. Such cat-
tween dogs with acute heart failure requiring hospital
egorization aids in teaching therapeutic protocols and
care and those with heart failure that can be treated on
constitutes a basis for stratification of subjects in clinical
an outpatient basis, these issues have been addressed
trials. The modified NYHA functional classification of
separately by the panel. Some animals presenting with
heart failure can be summarized as follows:
heart failure for the 1st time may have severe clinical
signs requiring aggressive therapy (eg, with additional
Class I describes patients with asymptomatic heart
afterload reducers or temporary ventilatory assistance)
disease (eg, CVHD is present, but no clinical signs are
that more typically would be reserved for those with re-
evident even with exercise).
fractory disease (see Stage D).
Class II describes patients with heart disease that
Stage D refers to patients with end-stage disease with
causes clinical signs only during strenuous exercise.
clinical signs of heart failure caused by CVHD that are
Class III describes patients with heart disease that
refractory to   standard therapy  (defined later in this
causes clinical signs with routine daily activities or
document). Such patients require advanced or special-
mild exercise.
ized treatment strategies in order to remain clinically
Class IV describes patients with heart disease that
comfortable with their disease. As with Stage C, the
causes severe clinical signs even at rest.
panel has distinguished between animals in Stage D
that require acute, hospital-based therapy and those
that can be managed as outpatients.
Functional classification systems share a common
problem in that they are based on relatively subjective
assessments of clinical signs that can change frequently This classification system emphasizes that there are
and dramatically over short periods of time. Further- risk factors and structural prerequisites for the develop-
more, treatments may not differ substantially across the ment of heart failure in CVHD. The use of this
functional classes. classification system is meant to encourage veterinary cli-
1144 Atkins et al
nicians to think about heart disease in a way analogous Diagnosis for Stage A
to the current clinical approach to cancer. This classifi-
Consensus recommendations:
cation system is designed to aid in:
Small breed dogs, including breeds with known
Developing screening programs for the presence of
predisposition to develop CVHD (eg, Cavalier
CVHD in dogs known to be at risk.
King Charles Spaniels, Dachshunds, Miniature
Identifying interventions that may (now or in the fu-
and Toy Poodles) should undergo regular evalua-
ture) decrease the risk of disease development.
tions (yearly auscultation by the family veter-
Identifying asymptomatic dogs with CVHD early in the
inarian) as part of routine health care.
course of their disease, comparable to   in situ  cancer,
Owners of breeding dogs or those at especially
so that they can perhaps be treated more effectively.
high risk, such as Cavalier King Charles Spaniels,
Identifying symptomatic dogs with CVHD so that
may choose to participate in yearly screening
these patients can be treated medically and either po-
events at dog shows or other events sponsored by
tentially cured (interventionally or surgically) or
their breed association or kennel club and con-
managed with their chronic disease.
ducted by board-certified cardiologists partici-
Identify symptomatic dogs with advanced heart failure
pating in an ACVIM-approved disease registry.
from CVHD and refractory to conventional therapy
these patients require aggressive or new treatment strat-
Therapy for Stage A
egies or potentially hospice-type end-of-life care.
Consensus recommendations:
Evaluating the Evidence for Efficacy and Safety
No drug therapy is recommended for any patient.
No dietary therapy is recommended for any pa-
In classifying dogs with CVHD according to their dis-
tient.
ease stage and clinical status and matching them with
Potential breeding stock should no longer be bred
diagnostic, pharmacologic, and dietary treatment recom-
if mitral regurgitation (MR) is identified early,
mendations, the consensus panel considered both the
during their normal breeding age of o6 8 years.
quantity and quality of evidence available to inform the
diagnostic and therapeutic decisions made in these pa-
Stage B These patients have a structural abnormality
tients. The heading   Consensus recommendation 
indicating the presence of CVHD, but have never had
preceding a diagnostic, therapeutic, or dietary recom-
clinical signs of heart failure. These patients are gener-
mendation indicates that the panelists were unanimous in
ally recognized during a screening or routine health
their opinion that the combination of available clinical
examination with a heart murmur typical of mitral
trial evidence, other published experimental or anecdotal
valve insufficiency.
evidence, clinical experience, and expert opinion indicate
that the potential benefit of the approach under discus-
Diagnosis for Stage B
sion clearly outweighs the potential risks to the patient
and minimizes financial impact on the client.
Consensus recommendations:
In situations in which the available evidence regarding
Thoracic radiography is recommended in all pa-
the efficacy of a diagnostic or therapeutic maneuver was
conflicting, weak, or absent and no consensus on a rec- tients to assess the hemodynamic significance of the
ommended course of action could be reached by the murmur andalsotoobtainbaseline thoracic radio-
panelists based on the available evidence and their col- graphs at a time when the patient is asymptomatic
lective clinical experience, the panel s opinions and for CVHD.
reasoning on clinically important issues are briefly sum- Blood pressure measurement is recommended for
marized. These bulleted summary statements are all patients.
In small breed dogs with typical murmurs, echo-
grouped together and summarized under the heading
  No consensus.  cardiography is recommended to answer specific
The panel recognized that there is considerable varia- questions regarding either cardiac chamber en-
tion in the scientific quality of the evidence available to largement or the cause of the murmur if those
support clinical decision making, and sought to include questions are not answered adequately by
topically relevant references. Whereas the status of a par- auscultation and thoracic radiography.
Echocardiography generally is indicated in larger
ticular recommendation (consensus versus no consensus)
reflects the collective judgment of the panel on each ques- breed dogs because the murmur of MR is more
tion addressed, no attempt was made to assign a specific likely to be related to other causes (eg, dilated
scientific grade or value to each included citation. cardiomyopathy).
Basic laboratory work (a minimum of hematocrit,
total protein concentration, serum creatinine concen-
Guidelines for Diagnosis and Treatment of CVHD
tration, and urinalysis) is indicated in all patients.
Stage A Dogs at high risk for development of heart
failure, but without apparent structural abnormality Because their prognosis and therapy may differ sub-
(no heart murmur is heard) at the time of examination. stantially, asymptomatic patients with murmurs of
Canine Chronic Valvular Heart Disease 1145
mitral valve insufficiency are further subcategorized into of b blockers for the treatment of dogs in Stage B2
2 groups based on the results of the above evaluation: are in progress.
No other pharmacologic treatments were recom-
Stage B1: Hemodynamically insignificant MR (defined
mended in Stage B2 by a majority of panelists. A
as radiographically or echocardiographically normal or
few panelists considered the use of the following
equivocally enlarged LA, LV, or both, with normal LV
medications for patients in Stage B2 under specific
systolic function; normal vertebral heart score on radi-
circumstances: pimobendan, digoxin, amlodipine,
ography; normotensive, normal laboratory results).
and spironolactone. The panel felt in general that
these treatment strategies needed additional inves-
Therapy for Stage B1 (both pharmacologic and di-
tigation into their efficacy and safety in this patient
etary) is identical for both small and large breed dogs.
population before a consensus recommendation
could be made.
Consensus recommendations:
Dietary treatment was recommended by a major-
ity of panelists in Stage B2, a minority of the panel
recommended no dietary changes. Principles guid-
Small and large breed dogs:
ing dietary treatment at this stage include mild
No drug or dietary therapy is recommended.
dietary sodium restriction and provision of a
Re-evaluation is suggested by either radiography
highly palatable diet with adequate protein and
or echocardiography with Doppler studies in ap-
calories for maintaining optimal body condition.
proximately 12 months (some panelists rec-
ommend more frequent follow-up in large dogs).
Larger breed dogs:
Generally, panelists who recommended treatment
Stage B2: Hemodynamically significant MR with car-
in smaller breed dogs strengthened their recom-
diac remodeling (defined as clearly enlarged LA, LV,
mendations promoting the use of both ACEI and b
or both); normotensive.
blockers in larger breed dogs in Stage B2.
Dietary treatment recommendations for larger breed
Therapy for Stage B2 (both pharmacologic and di-
dogs were the same as those for small breeds, empha-
etary) is controversial, and no consensus could be
sizing mild sodium restriction and adequate protein
reached with currently available evidence.
and caloric intake if changes were recommended.
No consensus:
Stage C Patients have a structural abnormality and
current or previous clinical signs of heart failure caused
Small breed dogs:
by CVHD. Stage C includes all patients that have had
an episode of clinical heart failure. Such patients stay
Angiogensin converting enzyme inhibitor (ACEI):
in this stage despite improvement of their clinical
For patients with clinically relevant left atrial en-
signs with standard therapy (even if their clinical signs
largement on either initial examination, or those
resolve completely). Guidelines for standard pharma-
in which the left atrium has increased in size dra-
cotherapy are provided for both in-hospital (acute)
matically on successive monitoring examinations, a
management of heart failure and for home care
majority of the panel members recommend initia-
(chronic) management of heart failure, as well as rec-
tion of therapy with an ACEI. Clinical trials
ommendations for chronic dietary therapy. Some
addressing the efficacy of ACEI for the treatment
patients that present in Stage C may have life-threat-
of dogs in Stage B2 have had mixed results either
ening clinical signs, and require more extensive acute
no effect or a small positive effect delaying the on-
therapy than is considered standard therapy. These
set of congestive heart failure.20 22 A minority of
acute care patients may share some medical manage-
the panel members recommend no therapy for
ment strategies with dogs that have progressed to
asymptomatic animals pending further clinical tri-
Stage D (refractory heart failure, see below). In Stage
als to examine the efficacy of therapy in this setting.
C, heart failure secondary to CVHD, the panel did not
b blockers: For patients with clinically relevant left
make clinically relevant therapeutic distinctions be-
atrial enlargement on either initial examination, or
tween small and larger breed dogs for either acute or
when the left atrium has increased in size dramat-
chronic medical management.
ically on successive monitoring examinations, a
minority of the panel members recommend initia-
tion of therapy with a low dosage of a b blocker, For both Stages C and D (CVHD patients with symp-
titrating to the highest tolerated dose over a period tomatic heart failure), the acute care of heart failure is
of approximately 1 2 months depending on the focused on regulating the patient s hemodynamic status
specific medication recommended. A majority of by monitoring (as well as possible under clinical circum-
the panel members recommend no b-blocker ther- stances) and pharmacologically optimizing preload,
apy for asymptomatic animals pending further afterload, heart rate, and contractility to improve car-
clinical trials to examine the efficacy of therapy in diac output, decrease the extent of mitral valve
this setting. Clinical trials addressing the efficacy regurgitation if possible, and relieve clinical signs associ-
1146 Atkins et al
ated with either low cardiac output or excessively in- For life-threatening pulmonary edema (expectora-
creased venous pressures (preload). The broad goals of tion of froth associated with severe dyspnea; diffuse
chronic (home care) management are focused on main- pulmonary opacity on thoracic radiographs; poor
taining these hemodynamic improvements to the extent initial response to furosemide bolus with failure of
possible, while providing additional treatments aimed at dyspnea and respiratory rate to improve over 2
slowing progression, prolonging survival, decreasing hours), furosemide is administered as a constant
clinical signs of congestive heart failure, enhancing exer- rate infusion (CRI) at a dose of 1 mg/kg/h after the
cise capacity, and otherwise improving quality life. initial bolus.23
Allow patient free access to water once diuresis has
begun.
Diagnosis for Stage C
Pimobendan, 0.25 0.3 mg/kg PO q12h Although
Consensus recommendations:
the clinical trial evidence supporting the chronic
use of pimobendan in the management of Stage C
Because of the relatively high prevalence of
heart failure from CVHD is stronger than for the
chronic tracheobronchial disease in the same pop-
acute situation, the recommendation to use pimo-
ulation at risk for CVHD, the presence of a typical
bendan in acute heart failure therapy is strongly
left apical regurgitant murmur in a coughing dog
supported by hemodynamic and experimental ev-
does not necessarily mean that the clinical signs are
idence24 27 as well as the anecdotal experience of
the result of CVHD.
the panelists.
A clinical database (including chest radiographs
Oxygen supplementation, if needed, can be admin-
and preferably an echocardiogram and basic labo-
istered via a humidity and temperature-controlled
ratory tests) must be obtained and examined
oxygen cage or incubator or via a nasal oxygen
carefully to accurately determine the cause of clin-
canula.
ical signs in animals with CVHD.
Mechanical treatments (eg, abdominal paracente-
Serum N-terminal pro-B-type naturetic peptide
sis and thoracocentesis) are recommended to
(BNP) concentrations should become increasingly
remove effusions judged sufficient to impair venti-
useful in determining the cause of clinical signs in
lation or cause respiratory distress.
dogs with CVHD. Although there is no doubt that,
Provide optimal nursing care, including mainte-
as a group, dogs with clinical signs caused by heart
nance of an appropriate environmental tempera-
failure have higher serum BNP concentrations
ture and humidity, increase in the head on pillows,
than those with clinical signs caused by primary
and placement of sedated patients in sternal posture.
pulmonary disease, the positive predictive value of
Sedation Anxiety associated with dyspnea should
any single BNP concentration, obtained by a com-
be treated. Narcotics, or a narcotic combined with
mercially available test, has not been adequately
an anxiolytic agent, are most often used by panelists.
characterized at the time of this writing (August
Butorphanol (0.2 0.25 mg/kg) administered IM or
2009) to make a consensus recommendation with
IV was the narcotic most often utilized for this pur-
regard to BNP testing.
pose; combinations of buprenorphine (0.0075
The signalment and physical examination can be
0.01 mg/kg) and acepromazine (0.01 0.03 mg/kg
helpful in determining the pretest probability of
IV, IM, or SQ) as well as other narcotics, including
heart failure as a cause of clinical signs in patients
morphine and hydrocodone, also have been utilized.
with CVHD. For example, obese dogs with no his-
CRI of sodium nitroprusside for up to 48 hours is
tory of weight loss are less likely to be in heart
often useful for life-threatening, poorly responsive
failure secondary to CVHD; dogs with marked si-
pulmonary edema (refer to Class D below for spe-
nus arrhythmia and relatively slow heart rates also
cific dosing recommendations).
are less likely to have clinical signs attributable to
CVHD.
No consensus was reached on the following acute care
Most of these dogs are middle-aged or older, and it
Stage C issues:
is always prudent to complete the database with a
CBC, serum biochemical profile, and urinalysis,
Care must be taken to monitor the blood pressure
especially if therapy for CHF is anticipated.
and respiratory response to narcotics and tranquil-
ilzers in the setting of acute heart failure. No
Acute (Hospital-Based) Therapy of Stage C
specific treatment or dosage regimen was used by
all panelists.
Consensus recommendations:
ACEI (eg, enalapril 0.5 mg/kg PO q12h). Although
treatment with ACEI is a consensus recommenda-
Furosemide The specific dosing of furosemide in
a dog with CHF should be related to the severity of tion for chronic Stage C heart failure and a majority
clinical signs and the response to initial therapy. of panelists also treat acute heart failure with ACEI,
Lower or higher doses (eg, 1 4 mg/kg) may be ap- the evidence supporting ACEI efficacy and safety in
propriate in specific cases. Repeated IV boluses or acute therapy when combined with furosemide and
a constant rate IV infusion may be indicated for pimobendan is less clear. There is, however, clear ev-
poorly responsive dogs. idence that the acute administration of enalapril plus
Canine Chronic Valvular Heart Disease 1147
furosemide in acute heart failure results in substantial mended the addition of digoxin in cases compli-
improvement in pulmonary capillary wedge pressure cated by persistent atrial fibrillation to slow the
when compared with the administration of furose- ventricular response rate. Some panelists also pre-
mide alone. scribe digoxin at this dosage for patients in Stage C
heart failure in the absence of sustained supraven-
Nitroglycerin 2% ointment, approximately 1/2 
paste per 10 kg body weight for 24 36 hours. Some tricular tachyarrhythmia, as long as no contra-
panelists recommend administering the ointment indication to digoxin is evident (eg, increased
in intervals (eg, 12 hours on, 12 hours off). Other serum creatinine concentration, ventricular ec-
panelists do not use nitroglycerin in this setting. topy, concerns over owner compliance, chronic
GI disease resulting in frequent or unpredictable
bouts of vomiting or diarrhea).
Home-Based (Chronic) Therapy for Stage C
Once heart failure signs have resolved, a stable
Consensus recommendations:
medication regimen has been instituted, and the
patient is eating and apparently feeling well, a mi-
Continue PO furosemide administration to effect,
nority of panelists recommend attempting a low
commonly at a dosage of 2 mg/kg q12h. The daily
dose, slow up-titration regimen of a b blocker.
furosemide dosage for dogs with CHF is wide and
There is no clinical trial evidence in dogs to sup-
can be as low as 1 2 mg/kg PO q12h to 4 6 mg/kg
port this recommendation. If prescribed, there is
PO q8h. The dosage must be titrated to maintain
no consensus regarding which specific b blocker to
patient comfort and with attention to effects on
use (carvedilol, atenolol, or metoprolol is the most
renal function and electrolyte status.
frequently prescribed). The purpose of b blockade
Chronic oral furosemide (doses 6 mg/kg q12h)
in this setting is related to potential long-term pro-
needed to maintain patient comfort in the face of
tective effects on myocardial function and
appropriate adjunct therapy indicates disease pro-
remodeling. These effects have been demonstrated
gression to Stage D.
in some experimental animal models31 and in hu-
Continue or start ACEI (eg, enalapril 0.5 mg/kg,
mans with heart failure, but not in clinical trials.
PO q12h) or equivalent dose of another ACEI
The presence of atrial fibrillation strengthens the
if approved for use. The labeled dosage range of
indication for b blockade (to slow the ventricular
enalapril is 0.25 0.5 mg/kg PO q12h; most panel-
response to atrial fibrillation) for those panelists
ists treat at the upper end of this range. Measure-
who recommended a b blocker.
ment of serum creatinine and electrolyte concen-
In patients taking a b blocker before the onset of
trations 3 7 days after beginning an ACEI is rec-
Stage C heart failure, the majority of panelists
ommended for animals with Stage C heart failure.
continue b blockade; some panelists would con-
Continue pimobendan (0.25 0.3 mg/kg PO
sider dosage reduction if needed clinically because
q12h).28 30
of clinical signs of low cardiac output, hypo-
Panelists recommend against starting a b blocker in
thermia, or bradycardia.
the face of active clinical signs of heart failure (eg,
Some panelists prefer administration of oral diltia-
cardiogenic pulmonary edema) caused by CVHD.
zem (several formulations are available, some
None of the panelists routinely use nitroglycerin in
sustained release) for chronic heart rate control in
the chronic treatment of Stage C heart failure.
atrial fibrillation.
Participation in a structured, home-based ex-
Some panelists find cough suppressants useful in
tended care program to facilitate body weight,
occasional patients in Stage C heart failure from
appetite, respiratory, and heart rate monitoring
CVHD.
while providing client support to enhance medica-
Some panelists find bronchodilators useful in oc-
tion compliance and dosage adjustments in
casional patients in Stage C heart failure from
patients with heart failure is encouraged.
CVHD.
No consensus was reached regarding the following
home-based (chronic) treatment strategies in Stage C:
Dietary Therapy for Stage C
Spironolactone (0.25 2.0 mg/kg PO q12 24h) was
Cardiac cachexia is defined as the unintentional loss
recommended by a majority of panelists as an ad-
of 47.5% of the patient s normal, predisease weight, not
junct for the chronic therapy of dogs in Stage C
including weight loss associated with the resolution of
heart failure. The primary purpose of spironolac-
edema or the removal of body cavity effusions. Cachexia
tone in this situation is thought to be aldosterone
has substantial negative prognostic implications, and is
antagonism. No clinically relevant diuretic effect
much easier to prevent that to treat.32
should be anticipated. This treatment now is ap-
proved in Europe at a dosage of 2 mg/kg/d.
Consensus recommendations:
Digoxin (0.0025 0.005 mg/kg PO q12h) with tar-
get plasma concentration 8 hours postpill of 0.8 Maintain adequate calorie intake (maintenance
1.5 ng/mL. For the chronic management of Stage calorie intake in Stage C should provide approxi-
C heart failure, a majority of panelists recom- mately 60 kcal/kg body weight) to minimize weight
1148 Atkins et al
loss (specifically muscle mass loss) that often oc- gies for Stage D patients proved difficult. As with Stage
curs in CHF. C, guidelines for drug treatment are provided for both in-
Specifically address and inquire about the occurrence hospital (acute) and for home care (chronic) manage-
of anorexia, and make efforts to treat any drug- ment of heart failure, and recommendations for chronic
induced or other identifiable causes of anorexia that dietary therapy are also given.
occur.
Record the accurate weight of the patient at every
Diagnosis for Stage D
clinic visit, and investigate the cause of weight gain or
Because Stage D heart failure patients are, by defi-
loss.
nition, refractory to the treatments for Stage C
Ensure adequate protein intake and avoid low-pro-
patients, defining refractory congestive heart fail-
tein diets designed to treat chronic kidney disease,
ure involves the same diagnostic steps outlined for
unless severe concurrent renal failure is present.
Stage C plus the finding of failure to respond to
Modestly restrict sodium intake, taking into con-
treatments outlined in the Stage C guidelines.
sideration sodium from all dietary sources
(including dog food, treats, table food, and foods
Acute (Hospital-Based) Therapy for Stage D
used to administer medications) and avoid any
(Refractory Heart Failure)
processed or other salted foods.
Monitor serum potassium concentrations and sup-
Consensus recommendations:
plement the diet with potassium from either
natural or commercial sources if hypokalemia is In the absence of severe renal insufficiency (ie,
identified. Hyperkalemia is relatively rare in pa- serum creatinine concentrations 4 3 mg/dL), ad-
tients treated for heart failure with diuretics, even ditional furosemide is administered IV as a bolus
in those concurrently receiving an ACEI in combi- at a dosage of 2 mg/kg followed by either addi-
nation with spironolactone.33 Diets and foods with tional bolus doses, or a furosemide CRI at a
high potassium content should be avoided when dosage of 1 mg/kg/h until respiratory distress (rate
hyperkalemia has been identified. and effort) has decreased, or for a maximum of
4 hours. As indicated above, the dosage or furose-
mide is a range and higher or lower doses may be
No consensus was reached on the following dietary ther-
appropriate for a given case.
apy for Stage C:
Continue to allow patient free access to water once
Consider monitoring serum magnesium concentra-
diuresis has begun.
tions, especially as CHF progresses and in animals
Fluid removal (eg, abdominal paracentesis, thor-
with arrhythmias. Supplement with magnesium in
acocentesis) as needed to relieve respiratory
cases in which hypomagnesemia is identified.
distress or discomfort.
Consider supplementing with n-3 fatty acids, espe-
In addition to oxygen supplementation as in Stage
cially in dogs with decreased appetite, muscle mass
C (above), mechanical ventilatory assistance may
loss, or arrhythmia.34
be useful to make the patient more comfortable, to
allow time for medications35 to have an effect; and
Stage D Patients have clinical signs of failure refrac-
to provide time for left atrial dilatation to accom-
tory to standard treatment for Stage C heart failure
modate sudden increases in mitral valve
from CVHD, as outlined above. Stage D heart failure
regurgitant volume in patients with acute exacer-
patients therefore should be receiving the maximal
bation of CVHD (eg, ruptured chordae tendinae
recommended (or tolerated) dosage of furosemide, an
with severe cardiogenic pulmonary edema) and
ACEI, and pimobendan, as outlined in the Stage C
impending respiratory failure.
guidelines above. Any indicated and tolerated antiar-
More vigorous afterload reduction in patients
rhythmic medication, needed to maintain sinus
that can tolerate arterial vasodilation. Drugs po-
rhythm (if possible) or regulate the ventricular re-
tentially beneficial include sodium nitroprusside
sponse to atrial fibrillation in a heart rate range of
(starting at 0.5 1 mg/kg/min), hydralazine (0.5
80 160/min, also should be used before a patient is
2.0 mg/kg PO), or amlodipine (0.05 0.1 mg/kg
considered refractory to standard therapy.
PO). Direct vasodilators should be started at a
low dosage and up-titrated hourly until adequate
Not surprisingly, there have been very few clinical tri- clinical improvement accompanied by a decrease
als addressing drug efficacy and safety in this patient of approximately 5 10% in systolic blood pressure
population. This leaves cardiologists treating patients is observed. These drugs are recommended in ad-
with heart failure refractory to conventional medical dition to an ACEI and pimobendan. The clinician
therapy with a perplexing variety of treatment options. should be mindful that any decline in blood pres-
Because of the relative lack of clinical trial evidence and sure will also depend on specific vasodilator drug.
the diverse clinical presentations of patients with end- For example, vasodilation effects are rapid onset
stage heart failure, development of meaningful consensus with nitroprusside, but slower with amlodipine.
guidelines regarding the timing and implementation of Caution is warranted to avoid serious, prolonged
individual pharmacologic and dietary treatment strate- hypotension (ie, monitor blood pressure and main-
Canine Chronic Valvular Heart Disease 1149
tain systolic arterial blood pressure 4 85 mmHg or weight or girth measurements) varied widely
mean arterial blood pressure 4 60 mmHg. Serum among the panelists.
creatinine concentration should be measured be- Spironolactone, if not already started in Stage C,
fore and 24 72 hours after administration of these is indicated for chronic treatment of Stage D
drugs. Patients in Stage D have life-threatening patients.
heart failure, and a trial of additional afterload re- b blockade generally should not be initiated at this
duction is warranted. The panel emphasized that stage unless clinical signs of heart failure can be
because afterload reduction may increase cardiac controlled, as outlined in Stage C.
output substantially in the setting of severe MR
and heart failure, administration of an arterial di-
No consensus was reached regarding the following
lator in this setting does not necessarily decrease
chronic Stage D therapeutic recommendations:
blood pressure.
Hydrochlorthiazide was recommended by several
panelists as adjunctive therapy with furosemide,
No consensus was reached regarding the following acute
utilizing various dosing schedules (including only
care Stage D recommendations:
intermittent use every 2nd 4th day). Some panel-
ists warned of the risk of acute renal failure and
Pimobendan dosage may be increased (off-label)
marked electrolyte disturbances, based on per-
to include a 3rd 0.3 mg/kg daily dose. Some panel-
sonal experience.
ists administer an additional dose of pimobendan
Pimobendan dosage is increased by some panelists
on admission of Stage D patients with acute
to include a 3rd 0.3 mg/kg daily dose (off-label use,
pulmonary edema. Because this dosage recom-
explanations and cautions apply as listed for in-
mendation is outside of the FDA-approved label-
hospital care, above).
ing for pimobendan, this use of the drug should be
Digoxin, at the same (relatively low) dosages rec-
explained to and approved by the client.
ommended by some panelists for Stage C heart
In animals judged to be too sick to wait for the
failure, was recommended for treatment of atrial
effects of oral afterload reduction or inotropic sup-
fibrillation for patients in Stage D, with the same
port (eg, pimobendan with or without hydralazine
cautions listed in Stage C above.
or amlodipine), nitroprusside (for afterload reduc-
Digoxin, at the same (relatively low) dosages rec-
tion in life threatening pulmonary edema) or
ommended by some panelists for Stage C heart
dobutamine (for inotropic support of the hypo-
failure, also was recommended by a minority of
tensive patient) must be administered by CRI.
panelists for all patients in Stage D in sinus rhythm,
Both drugs can be administered at dosages of 0.5
assuming no clear contraindication was present.
1.0 mg/kg/min and up-titrated every 15 30 minutes
Sildenafil (1 2 mg/kg PO q12h) is used by some
to a maximum of approximately 10 mg/kg/min.
panelists to treat Stage D heart failure caused by
These drugs, either separately or in combination,
CVHD or to treat advanced CVHD complicated
can be used for 12 48 hours to improve hemody-
by pulmonary hypertension.
namic status and control refractory cardiogenic
The majority of panelists felt that b blockade ini-
pulmonary edema. Continuous electrocardiograph-
tiated at an earlier stage of heart failure in CVHD
ic and blood pressure monitoring is recommended
should not be discontinued, but that dose reduc-
to minimize the potential risks of this therapy.
tion may be needed if shortness of breath could
Sildenafil (1 2 mg/kg PO q12h) is used by a minor-
not be controlled by the addition of other medica-
ity of panelists to treat acute exacerbations of
tions or if bradycardia, hypotension, or both were
Stage D heart failure caused by CVHD, even in
present.
the absence of diagnosed pulmonary hypertension.
b blockade still may be useful to decrease the ven-
Bronchodilators are recommended as an adjunct
tricular response rate in atrial fibrillation after
therapy in treating cardiogenic pulmonary edema
stabilization and digitalization.
in hospitalized patients by a minority of panelists.
Cough suppressants are recommended by a minor-
ity of panelists to treat chronic, intractable cough
Home-Based (Chronic) Stage D Therapy in Stage D patients receiving home care.
Bronchodilators are recommended by a minority
Consensus recommendations:
of panelists to treat chronic, intractable coughing
in Stage D patients receiving home careanelists.
Furosemide dosage should be increased as needed
to decrease pulmonary edema or body cavity effu-
Home-Based (Chronic) Dietary Therapy for Stage D
sions, if use is not limited by renal dysfunction
(which generally should be monitored 12 48 hours
Consensus recommendations:
after dosage increases). The specific strategy and
magnitude of dosage increase (eg, same dose in- All of the dietary considerations for Stage C
creased to 3 times per day versus 2 higher doses, (above) apply.
substituting 1 SC dose for a PO dose q48h, or In patients with refractory fluid accumulations, at-
flexible SC dose supplementation based on body tempts should be made to further decrease dietary
1150 Atkins et al
sodium intake if it can be done without compro- 19. Hunt SA, Baker DW, Chin MH, et al. ACC/AHA guidelines
for the evaluation and management of chronic heart failure in the
mising appetite or renal function.
adult: Executive summary. A report of the American College of
Cardiology/American Heart Association Task Force on Practice
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